Non-food warming drawers such as towel warmer drawers of conventional design are typically constructed as closed boxes of single wall or double wall construction with insulation or air in between, with front doors providing access to a sliding drawer horizontally aligned to access non-food items or objects (such as towels, robes, dishes, restaurant-ware, etc.) within the interior of the box. The front door(s) are often fixed in a vertical plane. Heating of the interior of the box is usually accomplished by a single cal rod (sheathed heating element), axial fan heaters, hot water, oil heat, or contact type heaters. The heat sources are typically arranged to conduct heat across an item in the drawer with the use forced air arrangements (such as a heater/fan or heater-blower combination) or by radiant heat arrangements where heat is radiated upwards from a heated pipe or a cal rod as a way to warm the interior of the box and to warm the non-food objects, such as towels, inside the box. However, warmer drawers for non-food objects that use such forced air methods in a closed chamber tend to have certain disadvantages. For example, a forced air heater/fan combination having a heating element in front of the fan and blowing hot air inside the enclosure tends to cause the heating element to continually heat up and draw excessive electrical current. In such arrangements, the heater usually receives only internal air as supplied by the fan and the heater remains in a mode of high output. The resulting high temperature is typically directed at the top or sides of the objects often causing hot spots that can burn the objects (such as heat sensitive objects such as towels and the like). The forcing of the air into the chamber also tends to result in air moving past the object without sufficiently warming the objects. In addition, direct contact with the heating element, if not shielded, can cause overheating, discoloration or burning of the objects. Further, in the event that the fan should stop or if air is somehow restricted, the fan can fail due to overheating, which may result in a “runaway” heating element. Accordingly, such conventional arrangements often require that a “fail-safe” type switch must be added which elevates the cost of the non-food warmer drawer.
According to other conventional designs, towel warmers with generally “airtight” enclosures have also been used. The airtight chambers typically use only the air inside the box, re-circulating it and heating (or reheating) the re-circulated air. However, these type of airtight chambers have certain disadvantages. For example, temperature overshoot and undershoot problems from the heating elements typically occur, resulting in temperatures within the airtight chambers that are too high and cause objects within the chamber such as towels to become too hot and discoloring (e.g. heat discoloration, scorching, burning, etc.). In order to protect the towels, many attempted solutions to reduce the temperature within the chambers have been used, but have not resulted in a satisfactory solution. In addition, the air within the airtight chambers poses other detrimental issues for the user. For example, because such warmers generally do not exhaust the heated air, any odor or smell from the objects tends to remain within the enclosure and adversely affect other objects. In some cases the smell may be so strong that the use of warmed objects such as towels becomes undesirable.
Other conventional non-food warmer drawers use a “pan” type of arrangement with a heating element (such as cal rod or the like) below the pan. However, such a conventional non-food warmer drawer design is essentially converting a conventional food warmer drawer to a non-food warmer application, which also tends to suffer from certain disadvantages. For example, when heating non-food objects such as towels, these pan-type warmer drawers tend to result in only the bottom of the towel getting warm and usually do not provide a desired uniform heating of the object(s). In some instances, before the towel's inside surfaces can be warmed, the exposed outer surfaces may burn or suffer other types of degradation associated with exposure to high temperature. In some conventional pan-type applications, a plate has been added within the box in an attempt to defuse the heat and prevent burning of the object(s). However, this purported “fix” usually only slows the warming of the object(s), which results in the object(s) needing to be in the pan for a longer period of time. When warming objects such as towels, the thermal energy necessary to penetrate the towel folds is a generally known problem with the use of pan (or shelf) type warmer drawers. Typically, when warming a stack of objects such as towels, as the “stack” of towels in the warmer drawer increases, the amount of thermal energy needed to heat towels to the desired level also increases.
The conventional non-food warmer drawers also suffer from other disadvantages. For example, the sensors used to detect the temperature of the objects in the warmer drawers are typically capillary tube device or the like, in which expanding gases within the tube, as temperature increases or decreases, transfers force or relaxes force to a mechanical switch, causing the switch to close or open for supplying electrical current to, or turning current off, to the cal rod or axial fan. The typical response time for these types of controls tends to be undesirably slow and often results in overshoots and undershoots in temperature. These characteristic temperature ranges and swings in conventional non-food warmer drawers, from power on and off cycling, tend to result in such conventional warmer drawers being designed to provide lower temperatures and longer times needed for warming of the objects (particularly for heat sensitive objects such as towels and the like). In addition, the undershoot of the temperature usually results in the user does not obtaining a desired temperature for the object. Thus the desired effects of receiving a properly warmed object, such as a warm towel to the skin and the ability to drive moisture out of a towel are reduced.
The conventional non-food warmer drawers also tend to suffer from certain other disadvantages. For example, certain conventional non-food warmer drawers often locate the heating elements with a combined fan (heater/blowers) on the top and sides of the warming chamber, and provide a cal rod (used in varying patterns) in the bottom of the box to provides radiant heat. The radiant heat tends to rise slowly, warming from the bottom to the top of the chamber. This radiant heat usually produces “hot spots” when reaching a pan or plate positioned above it. Such temperature hot spots are generally due to the radiant heat source being strongest (hottest) near the cal rod and decreasing in temperature as distance away from the cal rod increases.
The conventional non-food warmer drawers also tend to suffer from certain other disadvantages. For example, varying temperature levels within the box tend to cause difficulty in controlling and maintaining the temperature of the object. In some instances, temperature stratification or “layering” prevents even and uniform heating of the objects. In addition, startup times to attain the desired temperature in the box can be long due in part to the cal rod design. For example, too much heat too fast and the bottom of a heat sensitive object such as a folded towel will burn before the other parts of the towel reach the desired temperature. The conventional warmer drawers usually attempt to compensate for such problems by providing longer startup times. However, these long startup times generally prevent a user from simply “turning the warmer drawer on”, inserting a towel, and achieving an acceptably warm object in a reasonably short period of time. These conventional warmer drawers usually rely on startup times that are undesirably long in an effort to stabilize the temperature inside the box and bring the objects to a safe temperature without overheating. These types of conventional warmer drawers depend on the user accepting undesirably long startup times before using the object. If rushed, the object may not reach a desirable temperature and it can feel unacceptably cool to the touch. Further, as the cal rod cycles, temperature overshoots and undershoots typically result in the temperature on the object being too warm or too cool (depending on when the object is retrieved from the box).
The conventional non-food warmer drawers also tend to suffer from certain other disadvantages. For example, many conventional warmers drawers use knobs and slides to “set” and control mechanical switches for selecting the temperature for the objects. Such mechanical switches tend to have undesirable inaccuracies in their setting and the repeatability of a setting. The disadvantages of such mechanical switches tend to be due in part to the design of the non-food warmer drawer and method of heating, but also due to the inherent inaccuracy of the mechanical switches themselves. Mechanical control switches generally exhibit hysteresis, which contributes to inaccuracies in the ability of the control device to obtain a set point or repeat a function. For example, this can be seen in some conventional warmer drawers by turning the control switch to the right and stopping at a set point; then for comparison, turn the same mechanical switch past the desired set point and then turn the control to the left stopping at the set point. Both actions end with the same set point indicated on the switch but the resulting temperature in the box is often different. The inherent inaccuracies with the mechanical switching devices and controls tends to exacerbate the effects of temperature overshoots and undershoots and the resulting temperature variations experiences by the object. In order to compensate for (or mask) such inaccuracies, many conventional warmer drawers apply control selections that indicate low, medium, and hot (or the like), rather than a specific temperature setting. In such applications, a user generally cannot see the set point differences from one use to the next and may wonder why one day the object is warm and then another day the object is cool when presumably using the same selected settings. Temperature swings as much as 30 degrees or more are believed to occur in such instances have been seen and detract from the ability to provide accurate, rapid and uniform heating of non-food objects.
The conventional non-food warmer drawers also tend to suffer from certain other disadvantages. For example, conventional warmer drawers are typically designed for “built-in” installations, such as to cabinetry, or to a wall, or into another appliance, which tends to limit the available uses for the warmer drawer. The conventional warmer drawers generally do not permit usage as a freestanding unit, or as a mobile unit, or under a cabinet (e.g. suspended or the like), or in areas that do not have the ability to support a structural frame.
Therefore a need exists for a non-food warmer drawer in which more accurate and controlled heating of objects (e.g. towels, restaurant ware, etc.) is accomplished. There also exists the need for an accurate method of controlling the operations and settings of the non-food warmer drawer. There also exists a need for the controls of the non-food warmer drawer to be less susceptible to environmental influences. There also exists a need for a display device to permit a user to be able to view/see the operation, temperature indication(s), set point functions, and view of the contents of the chamber. There also exists a need for a non-food warmer drawer capable of remote control operation. There is a further need to accurately apply and control heat within the chamber of the non-food warming drawer. There is also needed for a non-food warmer drawer such that it can be used in any desirable location to suit the particular needs of a user.
Accordingly, it would be desirable to provide a non-food warming appliance such as a non-food warmer drawer, with any one or more of these or other advantageous features.